The present invention relates to an explosion proof gas-fired water heater whereby to shut off the gas burner and pilot upon the detection of abnormal life-threatening conditions in the vicinity of the gas-fired water heater.
Gas-fired water heaters can be hazardous if these are utilized in areas where there is a risk that combustible vapors may propagate in the area of such burners. Usually combustible vapors will accumulate on a floor surface and slowly build up and rise thus creating a large area of ignitable gas vapors. If such a cloud of vapors propagates into the combustion chamber of a gas-fired water heater they will ignite and cause a very serious explosion and usually destroying the gas-fired water heater and fragmenting the gas line to add further fuel to the fire. Needless to say, such explosion would be disastrous to any person in the immediate vicinity of the gas-fired water heater.
Another disadvantage of gas-fired water heaters is that they are usually installed in garages where fumes are released by automobiles due to gas leakage or paint, glues and other such combustible vapor generating products that we find in workshops where such items are usually stored. The basement is another hazardous location where we find these products. Various attempts have been made to deal with this problem but none have proven satisfactory.
A still further problem with gas-fired water heaters is that the air intake for the combustion chamber can become obstructed diminishing the supply of oxygen thus causing carbon monoxide which can seep into the air through the draft hood causing death to the residents.
It is a feature of the present invention to provide an explosion proof gas-tired water heater and wherein the supply of fresh air to the combustion chamber is made through at least one supply channel with the combustion chamber being sealed. One or more vapor detectors are associated with the channel to detect the presence of combustible vapors and the detectors operate switches to shut off the gas burner and pilot before the combustible vapors reach the gas burner and pilot through the air supply channel.
Another feature of the present invention is also to delay the propagation of the combustible vapors to the gas burner and pilot by disposing the intake port of the air supply channel at a predetermined distance elevated from the floor surface so that the combustion chamber has sufficient time to cool before the vapors can propagate into the combustion chamber through the supply channel.
Another feature of the present invention is to provide a gas-fired water heater wherein the fresh air intake port is provided in a support base of the water heater and wherein baffle walls are spaced from the intake port and the combustion chamber to delay the propagation of combustible vapors to the combustion chamber and further wherein the vapor detectors are disposed adjacent the fresh air intake port.
Another feature is to additionally provide a baffle and air dispenser perforated wall about the combustion chamber to optimize gas combustion.
A still further feature is to position the intake port of the supply channel substantially elevated from a floor surface such that explosive vapor clouds do not rise to the intake port to cause an explosion in the sealed combustion chamber.
A further feature is to provide a flame arrestor at the intake of the supply channel where it is easy to service and clean to ensure good supply of oxygen for the combustion.
Another feature is to provide a pressure detector in the supply channel to shut off the gas supply to the burner and pilot in the sealed combustion chamber should the supply channel intake become blocked or partly blocked to supply sufficient oxygen.
According to the above features, from a broad aspect, the present invention provides an explosion proof gas-fired water heater having a housing provided with a water reservoir and a sealed combustion chamber thereunder. A flue pipe is disposed above the combustion chamber and extends through the reservoir. A gas burner and pilot are provided in the combustion chamber. A gas supply line having a gas having gas supply shut-off valve is secured to the burner and pilot. A sealed combustible air channel lies fresh air to the combustion chamber and has an air supply intake disposed elevated from a floor surface of the water heater a distance of at least 40 inches whereby combustible vapors will not propagate to the air supply intake to enter the combustion chamber and reach the gas burner and pilot through the air supply channel. One or more vapor detectors are associated with the channel to detect the presence of combustible vapors. The vapor detectors are connected to a switching means to shut-off the gas burner and pilot before the combustible vapors reach the gas burner and pilot through the air supply channel.